Amputation of the lower limb is one of the most widely performed surgeries. The levels of amputation which decrease the length of the lower limb may generally be divided into two groups: those for which the bone surface after amputation is large enough to accept the distal delivery and those which require a deferred charge area. For above knee amputation, the weight bearing area is on the ischiatic apophysis. Conventional Gritti-Stokes amputation, which is an alternative to long femoral amputation, provides a terminal support. If femoral amputation is more proximal, the Gritti-Stokes amputation technique cannot be performed.
Two amputation levels can thus be distinguished: (i) those for which the distal end of the bony segment, after amputation, provides an area large enough to receive the weight of the patient, and (ii) those for which the severed bone does not provide an area large enough to receive the weight of the patient. The orthopedist technician (prosthetics and orthotics) should thus search for a different support, for instance situated on the ischiatic apophysis in the case of an above knee amputation. For the latter situation, there would be an advantage in providing a distal weight bearing area, avoiding a deferred charge on the ischiatic apophysis and freeing the gluteal zone.
When possible, a Gritti-Stokes amputation offers an interesting alternative in an above knee amputation, consisting in the fixation of the patella by mean of stitches, screws or K-wires. The patella is placed horizontal at the distal end of the femur bone stump. After consolidation, the patella's area supports the distal load. The hard socket goes up to the proximal aspect of the stump, without reaching the ischium. Traditionally this surgery has been indicated in amputations situated in the metaphysal area of the stump (just above the condyles). More proximal, the use of the patella is not recommended since i) its healing (fusion) to the femur is less predictable; and ii) it generates a bulky stump made of infolded muscles (quadriceps) still attached to the patella.
When Gritti-Stokes amputation cannot be implemented, a standard transfemoral amputation is performed; however the distal bony area is too small to receive and allow for end bearing. As a consequence, the patient must either rely on prosthesis with an ischiatic apophysis load, or an implant in the intramedulary canal. This will allow a prosthesis skeleton to be fixed directly on the implant. The latter technique allows the stump's distal load to rest on the prosthesis's skeleton, however, an important drawback is the risk of infection because of the implant passing through the skin. Another risk is the rupture of the intramedullar implant.